"Central Africa is currently hemorrhaging ivory, and these three countries are major conduits for trafficking illicit ivory from the region to international markets, particularly in Asia," the study's lead author Tom Milliken, director of TRAFFIC's Africa program, said in a statement.

Traffickers from China and other Asian countries were implicated in an increase in the size and number of large-scale ivory seizures, which have almost doubled in recent years.

The team found that confiscated ivory consignments weighing at least a ton rose from 17 between 1989 and 1997 to 32 between 1998 and 2006.

The report is based on an analysis of some 12,400 seizures from 82 countries logged on the world's largest database of elephant product seizures, the Elephant Trade Information System.

Ivory Trail

Demand for elephant ivory comes mainly from China, where it is shipped through ports such as Hong Kong, Macao, and Taiwan, researchers say. Other key destinations include Thailand, Philippines, and Japan.

The growth in large-scale seizures coincides with a period of massively increased trade between Africa and China, according to TRAFFIC's Richard Thomas, based at the organization's headquarters in Cambridge, England.

These trade ties have made illegal ivory shipments much easier to set up, Thomas said.

"The fact that they are shifting such large quantities of ivory suggests a move towards more organized crime," he added.

"It takes a well-organized operation to shift as much as a ton, which is about half a shipping crate. It's not like smuggling a piece of ivory in your hand luggage."

The trafficking is oiled by open-air markets in countries such as Angola, where illegal ivory is freely sold, the TRAFFIC team said.

Many ivory items offered at Angolan markets originated in neighboring countries such as the DRC, researchers discovered.

"For example, some of the animals that the ivory has been carved into [it] are Central African species," Thomas said. "They aren't animals that occur in Angola."

Susan Lieberman, director of WWF's Global Species Program, speaking from Rome, Italy, said increased seizures of such ivory surely means a surge in elephant killings by poachers.

Since there's no evidence the seized ivory had been stored, the implication is that it's fresh, she said.

Forest Elephants

The slaughter includes that of threatened populations of forest elephants in the Congo Basin, Lieberman added.

The research team is calling for a crackdown on poorly regulated African ivory markets that contravene CITES, an international treaty that monitors illegal trade in endangered wildlife.

"There is a CITES action plan to clamp down on illegal domestic ivory markets," Thomas, of TRAFFIC, said.

"Ethiopia has acted on it, and it's had an immediate effect. We'd like to see other countries follow suit."

In China, the team noted, there has been a significant improvement in law enforcement and policing of local markets, yet Chinese ivory traffickers in Africa are operating largely unchecked.

The report says that Chinese citizens have been arrested or detained or have fled in at least 126 major ivory seizures in African countries.

"It is imperative that China reaches out to the growing Chinese communities in Africa with a clear message that involvement in illegal ivory trade will not be tolerated," Milliken, the study's lead author, said.